Honestly I wouldn't recommend getting a 335i without CPO because repairs can be extremely expensive but it's perfectly fine if you have money aside for repairs. Things you should look for, 07' you should get one with sports package as it will come with the oil cooler (oil cooler is located in the front wheel well), try to see if there are signs that show the car has been modded. Also look for a car with good documentation of service records so you know if the car had past issues and the last one would be to get a PPI done at either an indy shop or a BMW dealer. That's all I can come up with now, hopefully someone else can add on with more information.

I got my 07 335 at 84k miles without a CPO (but did buy one with my credit union). The previous owners had EVERY SINGLE document when it got serviced. On top of that, the car's interior and exterior was IMMACULATE. That showed me the owners actually cared about the car. Every single thing functions as it should, and looks ridiculously modern. A lot of my friends think it's very newish model and are like "what the hell?" when I tell them the year. It all really depends on how the car was cared for.

service records of the last time a HPFP or injectors were done. I work at a Ford dealer but decent friends with a few BMW techs. The warranty is important if you have one that is older or never had replacements taken care of. Ill be selling my 09 soon and I know that question will be asked hundreds of times till I sell it. Although Im not the original owner I do have all the records for mine.

As with any vehicle without warranty, you're taking chances. The first step to take before purchasing any vehicle is exactly what you're doing now: recon.. or, research.

These forums provide you with a brilliant database to find known issues with the model you're researching. Take your time, read the threads and make notes.. copious amounts of notes.

Armed with knowledge, take the car to a BMW dealership and have them run the VIN so you can see the maintenance records and find out if the previous owner 'cared' for the car. Now you'll need to spend a few $ and have them go over the car with a fine-tooth comb: Are there any issues that they see. What maintenance is coming up?

As a previous poster stated, ensure you look at the vehicle condition: is it mint? It may only have 70k kms, but were they hard 70kms, or babied? How is the carpeting? Leather? Is it clean? Rock chips on the hood/side panels?

I did my research before I bought my 328xi - it has a year of factory warranty left and I spent $3k in extended warranty. For me, it is peace of mind knowing that should something go wrong, it'll be covered.

Don't forget, of course, that you are buying a BMW and that the maintenance will be more costly. Rather than taking it to the BMW dealership for maintenance (as there is no factory warranty left anyhow), talk to your local BMW club and see if they will give you the name of a reputable tech so you have a go-to guy for the things you can't / won't take care of yourself.

I would check service history with dealership (they can pull it up through VIN). If it's up to date, it should be fine. These are some notes I can think of...

Things known to have failed on the N54 motors are HPFP (most have been resolved through the recalls), injectors, and coil packs.

The turbo wastegate rattle can be annoying but it doesn't affect performance... The exhaust butterfly valve can rattle as well. Make sure the turbo's aren't shot (sounds like a siren).

Electric water pumps on all the e9x series seem to be a vulnerability. Some seem to fail at 50k, some at 80k, and some well past 120k (miles). Its like a crapshoot from what I've noticed so just keep that in mind.

Make sure that the software level is up to date or it might have the "lag" throttle response problem.

Everything else is mostly maintenance items...

If buying used, check to see if car has been chipped / tuned if that sorta thing bothers you.

i got my cpo 335 with 32k or so and have taken it in under warranty at least once a month.. high maintenance vehicles, would get costly without the warranty.. just a day before my maintenance went out the motor in my headlight went out and got a new one put in with only a slight attempt to stall me out of my warranty. :/ but yea warranty takes a lot of stress away

Carfax can pull up every single service record on a e9X. It won't be too detail but give you a general idea of what was done and when. That is provided the car was service at a new car dealership. Not your corner of the block used car lot.